IROS 2023: Minimally actuated tiltrotor for perching and normal force exertion

Dongjae Lee, Sunwoo Hwang, Changhyeon Kim, Seung Jae Lee and H. Jin Kim Abstract: This study presents a new hardware design and control of a minimally actuated 5 control degrees of freedom (CDoF) quadrotor-based tiltrotor. The proposed tiltrotor possesses several characteristics distinct from those found in existing works, including: 1) minimal number of actuators for 5 CDoF, 2) large margin to generate interaction force during aerial physical interaction (APhI), and 3) no mechanical obstru...

CDC 2023: Safety-Critical Control under Multiple State and Input Constraints and Application to Fixed-Wing UAV

Donggeon David Oh*, Dongjae Lee* and H. Jin Kim Abstract: This study presents a framework to guarantee safety for a class of second-order nonlinear systems under multiple state and input constraints. To facilitate real-world applications, a safety-critical controller must consider multiple constraints simultaneously, while being able to impose general forms of constraints designed for various tasks (e.g., obstacle avoidance). With this in mind, we first devise a zeroing control barrier f...

LCSS (CDC option) 2022: RISE-Based Trajectory Tracking Control of an Aerial Manipulator Under Uncertainty

Dongjae Lee, Jeonghyun Byun and H. Jin Kim Abstract: This letter presents a robust integral of the sign of the error (RISE)-based controller for an aerial manipulator consisting of a multi-rotor and a robotic arm which guarantees tracking error convergence to zero in the presence of uncertainties. To rigorously address underactuatedness issue, the system dynamics is decomposed into the two subsystems for which a robust controller is derived. As an intermediate result, if there exists no unc...

IROS 2021: Real-Time Motion Planning of a Hydraulic Excavator using Trajectory Optimization and Model Predictive Control

Dongjae lee*, Inkyu Jang*, Jeonghyun byun, Hoseong Seo and H. Jin Kim Abstract: Automation of excavation tasks requires real-time trajectory planning satisfying various constraints. To guarantee both constraint feasibility and real-time trajectory re-plannability, we present an integrated framework for real-time optimization-based trajectory planning of a hydraulic excavator. The proposed framework is composed of two main modules: a global planner and a real-time local planner. The global p...

RAL (ICRA option) 2021: Aerial Manipulator Pushing a Movable Structure using a DOB-based Robust Controller [IEEE ICRA 2021 Best Paper Award on Unmanned Aerial Vehicles]

Dongjae lee, Hoseong Seo, Inkyu Jang, Seung Jae Lee and H. Jin Kim Abstract: This paper deals with the problem of an aerial manipulator pushing a movable structure. Contrary to physical interaction with a static structure, suitable consideration of the interacting force during the motion of the structure is required to stably perform this movable structure interaction. To accomplish the task of pushing a structure while ensuring the stability of the aerial manipulator, we present a nonlinea...

MS Thesis 2020: Opening a Hinged Door with an Aerial Manipulator using Model Predictive Control

Abstract: From aerial pick-and-place to aerial transportation, aerial manipulation has been extensively stud-ied in recent years thanks to its mobility and dexterity, each of which is a merit of an aerial vehicleand a robotic arm. However, to fully harness the concept of aerial manipulation, more complextasks including interaction with movable structures should also be considered. Among varioustypes of movable structures, this paper presents a multirotor-based aerial manipulator op...

ICRA 2020: Aerial Manipulation using Model Predictive Control for Opening a Hinged Door

Dongjae Lee, Hoseong Seo, Dabin Kim and H. Jin Kim Abstract: Existing studies for environment interaction with an aerial robot have been focused on interaction with static surroundings. However, to fully explore the concept of an aerial manipulation, interaction with moving structures should also be considered. In this paper, a multirotor-based aerial manipulator opening a daily-life moving structure, a hinged door, is presented. In order to address the constrained motion of the structure a...

ICCAS 2019: Model Predictive Control for an Aerial Manipulator Opening a Hinged Door

Dongjae Lee, Dohyun Jang, Hoseong Seo and H. Jin Kim Abstract: Aerial manipulation has been widely studied to be employed in various tasks such as exploration and transportation. To incorporate aerial manipulation into more sophisticated tasks like pulling or pushing a heavy cargo, an active interaction with surrounding structures should be considered. Unlike physical contact with a static structure which was mainly studied in previous papers, interaction with a movable structure require...